嗯再问你一提,根号1-sin40度cos40度/cos40度-根号1-sin2(为平方)50度=

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嗯再问你一提,根号1-sin40度cos40度/cos40度-根号1-sin2(为平方)50度=

√(1-2sin40°cos40°)/[cos40°-√(1-sin^50°)]
=(cos40°-sin40°)/[cos40°-cos50°]
=1(∵sin40°=cos50°).

sqrt(1-sin(40)cos(40))/cos(40)-sqrt(1-sin^2(50))
=sqrt(1/cos^2(40)-sin(40)/cos(40))-sqrt(cos^2(50))
=sqrt((sin^2(40)+cos^2(40))/cos^2(40)-tg(40))-cos(50)
=sqrt(tg^2(40)+1-tg(40))-cos(50)

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sqrt(1-sin(40)cos(40))/cos(40)-sqrt(1-sin^2(50))
=sqrt(1/cos^2(40)-sin(40)/cos(40))-sqrt(cos^2(50))
=sqrt((sin^2(40)+cos^2(40))/cos^2(40)-tg(40))-cos(50)
=sqrt(tg^2(40)+1-tg(40))-cos(50)
=sqrt(tg(40)-1/2)^2+3/4)-cos(50)

sqrt中不是完全平方数,到此为止

如果是 sqrt(1-2sin(40)cos(40)) ?

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